This is an application for an ADAMHA RSDA level II. The applicant has a long-standing interest in the regulation of opioid peptides, as well as other peptide neurotransmitters; this regulation may be important in understanding the molecular basis of drug abuse. The candidate's immediate career goals involve investigations of various neuropeptide-processing enzymes, such as carboxypeptidase E (CPE), a dynorphin-processing endopeptidase, and other enzymes. A key issue concerns the regulation of various enzymes, and the implications for neuropeptide production. Long-term career goals involve applying the information from studies on the regulation of enzymes towards the in vivo regulation that may occur upon drug addiction. The RSDA award will enhance the research activities of the applicant by freeing him of the responsibilities of managing the Medical Pharmacology course. The applicant, currently a co-organizer of the course, would be relieved of these obligations if the award is made. Also, other administrative and teaching duties would be reduced so that >80% effort could be directed towards research. The environment at Albert Einstein College is highly supportive, with many active research groups studying related topics: signal transduction mechanisms, neurotransmitter receptors, gene regulation, protein structure and function, and more. The research plan is focused on the regulation of CPE, an essential enzyme in the production of opioid and other peptide neurotransmitters. The overall objective of these studies is to examine the mechanisms by which CPE is regulated. In cell culture systems, various treatments will be examined for an effect on the levels of CPE mRNA and enzymatic activity. Various soluble and membrane-bound forms of CPE will be examined; since membrane-bound CPE is less active than the soluble forms, this may represent an important step for enzyme regulation. The post- translational modification responsible for the differences between various forms of CPE will be determined, and the enzymes that process CPE will be identified. The structure-function relationship of CPE will be examined using a variety of techniques with native and mutant forms of CPE. The CPE gene will also be studied, with the focus on understanding the regulatory elements that give rise to the tissue-specific and pharmacologically-induced regulation of CPE mRNA. In addition to these studies on CPE, the co-regulation of CPE and other peptide processing enzymes (prohormone convertases, amidating enzymes) will also be examined. The results of these studies will provide a better understanding of the mechanisms for the regulation of CPE and other neuropeptide-processing enzymes.